Suburbs spread farther afield as more families do the math

"A great migration is rapidly changing the face -- and the faces -- of Chicago and its suburbs. Although there has been an outward exodus for more than a century, new census and other government data show that the edges of the metropolitan area are being pushed ever farther out, and at a much faster rate than had been predicted.

It's not just more people in places they weren't before. This trend has political, environmental, economical and cultural ramifications.

Rising populations give suburbs increasing clout. Some of the country's richest farmland is being paved over. More mileage driven by more cars increases the demand for foreign oil. Longer commutes mean less time at home with families. When large numbers of children enter a community they put a heavier burden on the tax base, with needs for more schools, parks, etc."